Show HN: Pu.sh – a full coding-agent harness in 400 lines of shell

Pu.sh ships a coding-agent harness in about 400 lines of shell, using only sh, curl, and awk. It supports Anthropic and OpenAI, 7 tools, REPL, auto-compaction, checkpoint/resume, pipe mode, and 90 no-API tests. It excludes TUI, streaming, images, OAuth, and Windows.

Why it matters: HKR-H/K/R all pass, but this is a small Show HN open-source tool, not a model or platform release. HN frontpage plus a reproducible 400-line implementation clears the featured bar.